The families of flowering plants

L. Watson and M.J. Dallwitz

Piperaceae C.A. Agardh

Excluding Peperomiaceae.

Habit and leaf form. Small trees, or shrubs, or lianas; bearing essential oils. Plants succulent, or non-succulent. Self supporting, or climbing. Stem growth conspicuously sympodial (often), or not conspicuously sympodial. Mesophytic. Leaves alternate; spiral; ‘herbaceous’, or fleshy; petiolate; sheathing. Leaf sheaths not tubular; with free margins. Leaves gland-dotted, or not gland-dotted; aromatic; simple. Lamina entire; pinnately veined, or palmately veined (or pinnate-palmate); cross-venulate. Leaves stipulate. Stipules intrapetiolar (adnate). Lamina margins entire. Leaf development not ‘graminaceous’.

Leaf anatomy. The leaf lamina dorsiventral. Leaves with ‘pearl glands’ (sometimes), or without ‘pearl glands’. Hydathodes commonly present. Stomata present; usually mainly confined to one surface (abaxial); cyclocytic, or anisocytic. Hairs present (but never forming a dense covering); eglandular and glandular; mostly multicellular. Multicellular hairs multiseriate. Adaxial hypodermis commonly present. Lamina with secretory cavities, or without secretory cavities. Secretory cavities when present, containing mucilage. The mesophyll with spherical etherial oil cells (usually with secretory cells having translucent or brown, often oily contents, these sometimes appearing as transparent or opaque dots); containing crystals. The crystals druses, or solitary-prismatic (acicular).

Axial (stem, wood) anatomy. Cork cambium present; initially superficial. Nodes tri-lacunar to multilacunar (with three to five or more traces). Primary vascular tissues disposed monocot-like, and consisting of scattered bundles, or comprising two or more rings of bundles; collateral. Internal phloem absent. Medullary bundles present. Secondary thickening developing from a conventional cambial ring to anomalous (see illustration). The anomalous secondary thickening from a single cambial ring.

The vessel end-walls scalariform, or simple. The axial xylem without fibre tracheids; with libriform fibres; including septate fibres, or without septate fibres. The parenchyma paratracheal. ‘Included’ phloem absent. The wood storied to not storied.

Reproductive type, pollination. Fertile flowers hermaphrodite. Plants hermaphrodite.

Inflorescence, floral, fruit and seed morphology. Flowers aggregated in ‘inflorescences’; in spadices or in spikes. Inflorescences axillary, or leaf-opposed (usually), or epiphyllous; in spikes or spadices — these simple or umbellate. Flowers bracteate; minute to small.

Perianth absent.

Androecium 1–10. Androecial members united with the gynoecium (adnate to its base), or free of the gynoecium; free of one another to coherent; often more or less 1 adelphous (the filaments joined at the base). Androecium exclusively of fertile stamens, or including staminodes. Staminodes when present, in the form of arrested stamens. Stamens 1–10. Anthers dehiscing via longitudinal slits (via two slits); extrorse; tetrasporangiate. Endothecium developing fibrous thickenings. Anther epidermis persistent. Microsporogenesis simultaneous. Anther wall initially with one middle layer, or initially with more than one middle layer (1 or 2); of the ‘monocot’ type. Tapetum glandular. Pollen grains aperturate to nonaperturate; when detectably aperturate, 1 aperturate; sulcate; 2-celled.

Gynoecium (2–)4 carpelled. The pistil 1 celled. Gynoecium syncarpous; synstylovarious; superior. Ovary 1 locular. Stigmas 1–5; dry type; papillate; Group II type. Placentation basal. Ovules in the single cavity 1; ascending; orthotropous; bitegmic; crassinucellate. Outer integument contributing to the micropyle, or not contributing to the micropyle. Embryo-sac development Fritillaria-type. Polar nuclei fusing prior to fertilization. Antipodal cells formed; proliferating. Synergids poorly differentiated. Endosperm formation cellular, or nuclear. Embryogeny piperad.

Fruit fleshy; indehiscent; a berry. Gynoecia of adjoining flowers combining to form a multiple fruit. Fruit 1 seeded. Seeds scantily endospermic. Perisperm present (copious). Embryo rudimentary at the time of seed release.

Seedling. Germination phanerocotylar.

Physiology, phytochemistry. CAM. Anatomy non-C4 type (Piper). Not cyanogenic. Alkaloids present (nearly always), or absent. Iridoids detected (dubiously), or not detected. Saponins/sapogenins present (?), or absent. Proanthocyanidins absent. Flavonols absent. Ellagic acid absent (2 genera). Aluminium accumulation demonstrated, or not found. Sieve-tube plastids S-type.

Geography, cytology. Sub-tropical to tropical. Pantropical. X = 12(?).

Taxonomy. Subclass Dicotyledonae; Crassinucelli. Dahlgren’s Superorder Nymphaeiflorae; Piperales. Cronquist’s Subclass Magnoliidae; Piperales. APG III core angiosperms; Superorder Magnolianae. APG IV Order Piperales.

Species 2000. Genera 7, or 8; Circaeocarpus (= Zippelia), Lindeniopiper, Ottonia, Piper, Pothomorphe, Sarcorhachis, Trianaeopiper, Zippelia (~ Piper).

Economic uses, etc. Piper nigrum is the source of black and white peppercorns (ripe and unripe, respectively); others are widely grown as houseplants.

Illustrations. • Le Maout and Decaisne: Piper sensu lato. • Piper guineense: Thonner. • Piper zeylanicum, as P. thwaitesii: Trimen, Ill. Fl. Ceylon (1898). • Piper (fruiting inflorescence). • Pearl gland from leaf of Piper (Artanthe) sp., with anatomical details of Peperomiaceae leaves (Piper spp.): Solereder, 1908. • TS stems of Piper carpunya and P. fluminense, showing peculiar vascular anatomy (with Peperomia incana, Peperomiaceae); Solereder, 1908.

We advise against extracting comparative information from the descriptions. This is much more easily achieved using the DELTA data files or the interactive key, which allows access to the character list, illustrations, full and partial descriptions, diagnostic descriptions, differences and similarities between taxa, lists of taxa exhibiting or lacking specified attributes, distributions of character states within any set of taxa, geographical distribution, genera included in each family, and classifications (Dahlgren; Dahlgren, Clifford, and Yeo; Cronquist; APG). See also Guidelines for using data taken from Web publications.

Cite this publication as: ‘Watson, L., and Dallwitz, M.J. 1992 onwards. The families of flowering plants: descriptions, illustrations, identification, and information retrieval. Version: 5th March 2018.’.